Which flight condition is primarily responsible for the risk of stall?

• A. High angle of attack.
• B. Low angle of attack.
• C. Excessive speed.
• D. Negative climb rate.

Answer: (C)

Stall risk is driven by angle of attack—the wing’s orientation to the oncoming air. When the angle of attack exceeds the wing’s critical value, the airflow can no longer follow the wing surface, the boundary layer separates, lift collapses, and a stall occurs. This is why high angle of attack is the primary flight condition that leads to a stall. Speed plays a role in stall speed—the speed at which you would stall for a given weight and configuration—but by itself, excessive speed does not cause a stall; you could stall at high speed if you hold the wing at a very high angle. Low angle of attack reduces stall risk, and a negative climb rate describes descent rather than the lift condition that causes a stall. So the condition that most directly creates stall risk is a high angle of attack.